NanoSIMS analysis of organic carbon from the Tissint Martian meteorite : Evidence for the past existence of subsurface organic-bearing fluids on Mars

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Lin, Yangting ; El Goresy, Ahmed ; Hu, Sen ; Zhang, Jianchao ; Gillet, Philippe ; Xu, Yuchen ; Hao, Jialong ; Miyahara, Masaaki ; Ouyang, Ziyuan ; Ohtani, Eiji ; Xu, Lin ; Yang, Wei ; Feng, Lu ; Zhao, Xuchao ; Yang, Jing ; Ozawa, Shin:
NanoSIMS analysis of organic carbon from the Tissint Martian meteorite : Evidence for the past existence of subsurface organic-bearing fluids on Mars.
In: Meteoritics & Planetary Science. Bd. 49 (Dezember 2014) Heft 12 . - S. 2201-2218.
ISSN 1945-5100
DOI: https://doi.org/10.1111/maps.12389

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Abstract

Two petrographic settings of carbonaceous components, mainly filling open fractures and occasionally enclosed in shock-melt veins, were found in the recently fallen Tissint Martian meteorite. The presence in shock-melt veins and the deuterium enrichments (δD up to +1183‰) of these components clearly indicate a pristine Martian origin. The carbonaceous components are kerogen-like, based on micro-Raman spectra and multielemental ratios, and were probably deposited from fluids in shock-induced fractures in the parent rock of Tissint. After precipitation of the organic matter, the rock experienced another severe shock event, producing the melt veins that encapsulated a part of the organic matter. The C isotopic compositions of the organic matter (δ13C = −12.8 to −33.1‰) are significantly lighter than Martian atmospheric CO2 and carbonate, providing a tantalizing hint for a possible biotic process. Alternatively, the organic matter could be derived from carbonaceous chondrites, as insoluble organic matter from the latter has similar chemical and isotopic compositions. The presence of organic-rich fluids that infiltrated rocks near the surface of Mars has significant implications for the study of Martian paleoenvironment and perhaps to search for possible ancient biological activities on Mars.